A protester who was arrested and released by police on the same day twice this month says officers intimidated him during his detention at a Sunday rally.

Billy Chiu Hin-chung was protesting with about 200 fellow advocates for the city’s autonomy at Chief Executive Leung Chun-ying’s town hall meeting in Kwun Tong on Sunday when he was held for trying to break away from the cordoned demonstration area.

I was inciting the public when I raised my hands, and I was trying to grab a gun from a policeman when I lowered my hands – the police can arrest me either way

protester Billy Chiu Hin-chung

Chiu said he was detained by the police for an “unnecessarily long time” and that during the nine hours he was held one officer tried to intimidate him into fighting him. He believed it was an attempt to “find an excuse” to charge him with assaulting a police officer.

Chiu was arrested on August 4 for “attempting to grab a police gun” during a protest supporting primary teacher Alpais Lam Wai-sze – an incident later clarified by police as “a misunderstanding”.

A police statement said both arrests were made based on “reasonable suspicion” and accusations against the police for indiscriminate arrest were “unfounded”. It said Chiu was released on Sunday because he refused to accept any form of release on bail, and that he was warned of a possible arrest or charge against him in future.

“I was inciting the public when I raised my hands, and I was trying to grab a gun from a policeman when I lowered my hands – the police can arrest me either way,” Chiu said on Wednesday.

“[By arresting me,] the police were trying to exhaust the activists’ willpower and convince us that showing up at protests would not change anything.”

Chiu said he had already sent a letter to Police Commissioner Andy Tsang Wai-hung demanding a public apology from him.